st: RE: Lags (verification)

Hi, I would like to regard the years as the time variable, I think. It is a panel, so I have tsset as follows (wave is the year variable): tsset pid wave.
I have a variable called, say, VAR and I would like to create a new variable LAGVAR, which contains its lags taking into consideration that there is a gap of 2 years between each waves and in one case the gap is 3 years. Could you suggest how I could change what I have done to achieve this purpose? Would numbering the waves 1 to 5 still be appropriate? Thanks. I include what I did before again.
tsset pid wave
ge LAGVAR1=VAR-L2.VAR
foreach i of numlist 2000 { replace LAGVAR1=. if
wave==`i' }
ge LAGVAR2=LAGVAR-L3.LAGVAR
foreach i of numlist 1991 1993 1995 1997 { replace
LAGVAR2=. if wave==`i' }
ge LAGVAR=LAGVAR1 if LAGVAR1~=.
replace LAGVAR=LAGVAR2 if LAGVAR2~=.
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